Engine Size: 2.0 4L
Refrigerant Type: 134a
Ambient Temp: 90
Pressure Low: 70
Pressure High: 115
Shop says bad compressor so I checked it.
engine off, HI=120, Lo=115. Startup, turn on A/C, after a few seconds compressor engages, clutch is turning, at 1500-2000 rpm Hi pressure stays at 115 but every now and then jumps to 140psig (maybe once in 5 minutes) and immediately drops back to 115 psig....stays rock steady at that value. The Lo drops to 70-80 psig and holds, fluctuates a little with engine speed. No cooling, vent temp stays at 90. Electrical seems to be fine. Cooling fan on....I sprayed a little water on the condenser and the suction moved a little but little change on the high side.
Cond Temp: In=116, Out=117
Evap Temp: In=127, Out=126
Shop manual says V5 variable compressor, no triple switch, only safety pressure switch, compressor on all the time when A/C on, TX valve. I cant see the full compressor name plate but I see Model 715401, SAE J639, Code 112072, and HI.
No unusual sounds from compressor but clutch definitely engages. No leaks and it does have dye in it. I removed high pressure hose between compressor and condenser, drained, blew out, the oil looks clean, no specs or shavings, only a green shade from the die. Looked into compressor ports, no debris, suction screen looks clean.
My only conern with the diagnosis, although it may be right, is that the high pressure port is between the recvr/drier and the TX valve. If the TX valve is closed and the recvr or condenser is plugged you wouldnt see a change in Hi pressure. But that would mean two plugged devices. The discharge hose was clear...no debris.
Likely the compressor?
Update: I see this compressor has a compressor control valve....could these be symptoms of failing valve?
Edited: Thu August 30, 2012 at 11:08 PM by efxengr
This does sound like a variable compressor stuck at zero displacement. Often, replacing the control valve cures it.
Are V5 control valves standard interchangeble items? I notice suppliers have the valves, some cross referenced by Car/MY, etc., but no cross reference to the compressor no. If I pull the valve out...with car info and compressor number should I be able to get the proper replacement? I notice the valves at ACKits.com are color coded.
Also, can the valve be cleaned and serviced or better to replace? I notice from the diagram it looks like it has some sealed internal components.
The different valves have slightly different pressure settings, you should use the same one to match the design of your system, but others would work to some degree at least to confirm that the rest of the compressor is OK. The color dot is on the end on the outside. System pressure must be zero before trying to remove the valve.
Great, thanks. I want to confirm if its the entire compressor first but, might as well have the right valve.
Yep, it was the compressor control valve. Stuck a new one in...bought it from the dealer with VIN number and it was a perfect match. A word of warning, be careful cleaning dirt/grime off the compressor to get at the control vavle....I brushed the color dot right off with a plastic brush. Fortunately, I remembered it was black and the VIN confirmed it. A/C is right on spec or better.
Quote from the shop for 'new compressor, etc.': $835
Parts (Valve, acc/dryer, oil, refrigerant, o-rings): $145
Diagnosing/Repairing with my ACkits DIY Starter kit: Priceless
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